"If I Only Had a Brain" (also "If I Only Had a Heart" and "If I Only Had the Nerve") is a song by Harold Arlen (music) and Yip Harburg (lyrics). The song is sung in the 1939 film The Wizard of Oz by the character Scarecrow, played by Ray Bolger, when he meets Dorothy, played by Judy Garland. The characters pine about what each wants from the Wizard. It was also sung in Jeremy Sams and Andrew Lloyd Webber's 2011 musical adaptation with an additional reprise called "If We Only Had a Plan" when the characters discuss how to rescue Dorothy in Act II.
Originally written by Arlen and Harburg as "I'm Hanging On To You" for the 1937 Broadway musical Hooray for What!, the song was ultimately dropped from that show, and when the pair was later hired to do the songs for Oz, Harburg simply wrote new lyrics to his catchy melody, a syncopated schottische in the style of tunes used for vaudeville soft shoe and sand dancing.